β-sitosterol, a phytosterol found in OO, inhibited significantly the growth of COLO 320 DM cells, in a dose-dependent way, caused apoptosis by scavenging ROS, and suppressed the expression of beta-catenin and proliferating cell nuclear antigen (PCNA) in human colon cancer cells [42]. The gene discussed is PCNA; the disease is malignant colon neoplasm.